Federal Reserve Chairman Ben Bernanke defended the central bank's efforts to revive the US economy from international criticism. He stated the Fed is not responsible for artificially boosting rival currencies, and the other nations should let market forces determine exchange rates.

Speaking before the International Monetary Fund meeting in Tokyo, Bernanke on Sunday refuted criticism that the Fed’s asset purchases and low interest rates are mainly driving capital flows to emerging market economies. The Fed last month embarked on its third major bond-purchase program, this time buying $40 billion of mortgage-backed securities every month until unspecified improvement in the economy.

Bernanke said he was “sympathetic” to the problems associated with overly hot flows, namely undesirable currency appreciation, asset bubbles or inflation or economic disruptions when hot money goes back out.

His response was two-fold — one, that basically, the Fed isn’t driving capital inflows to emerging-market nations; and two, that emerging-market economies should accept currency appreciation.

“To be sure, highly accommodative monetary policies in the United States, as well as in other advanced economies, shift interest rate differentials in favor of emerging markets and thus probably contribute to private capital flows to these markets,” Bernanke said, according to a transcript of his remarks. “I would argue, though, that it is not at all clear that accommodative policies in advanced economies impose net costs on emerging market economies.”

Bernanke cited IMF and other research showing that differences in growth prospects are the most important determinant of capital flows. He points out that capital flows have diminished recently even as the Fed and other central banks have continued to ease.

He also took the time to throw criticism back at emerging-market country policymakers.

“In some emerging markets, policymakers have chosen to systematically resist currency appreciation as a means of promoting exports and domestic growth. However, the perceived benefits of currency management inevitably come with costs, including reduced monetary independence and the consequent susceptibility to imported inflation. In other words, the perceived advantages of undervaluation and the problem of unwanted capital inflows must be understood as a package — you can’t have one without the other.”

The most pointed international criticism of the Fed has come from Brazil, where Finance Minister Guido Mantega has said he’d like to see the U.S. stimulate the economy by fiscal instead of monetary means.

Mantega on Friday said Brazil will take “whatever measures it deems necessary” to counter currency appreciation.

Already, Brazil has erected a 6% tax known as the IOF on overseas loans.

“Advanced countries cannot count on exporting their way out of the crisis at the expense of emerging-market economies,” Mantega said, according to a Dow Jones Newswires account. “Currency wars will only compound the world’s economic difficulties,” he added.

China’s currency, which trades in a narrow band, recently hit a high against the dollar as the Treasury Department delayed a report on currency manipulation.

For his part, Bernanke said the Fed can only do so much to help the U.S. economy.

“Although we expect our policies to provide meaningful help to the economy, the most effective approach would combine a range of economic policies and tackle longer-term fiscal and structural issues as well as the near-term shortfall in aggregate demand,” he said.